/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.feilong.lib.beanutils;

import java.beans.PropertyDescriptor;
import java.lang.ref.Reference;
import java.lang.ref.SoftReference;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.WeakHashMap;

import org.apache.commons.beanutils.DynaBean;

/**
 * Implementation of <code>DynaClass</code> for DynaBeans that wrap
 * standard JavaBean instances.
 *
 * <p>
 * It is suggested that this class should not usually need to be used directly
 * to create new <code>WrapDynaBean</code> instances.
 * It's usually better to call the <code>WrapDynaBean</code> constructor directly.
 * For example:
 * </p>
 * <code><pre>
 *   Object javaBean = ...;
 *   DynaBean wrapper = new WrapDynaBean(javaBean);
 * </pre></code>
 * <p>
 *
 * @version $Id$
 */
public class WrapDynaClass implements DynaClass{

    // ----------------------------------------------------------- Constructors

    /**
     * Construct a new WrapDynaClass for the specified JavaBean class. This
     * constructor is private; WrapDynaClass instances will be created as
     * needed via calls to the <code>createDynaClass(Class)</code> method.
     *
     * @param beanClass
     *            JavaBean class to be introspected around
     * @param propUtils
     *            the {@code PropertyUtilsBean} associated with this class
     */
    private WrapDynaClass(final Class<?> beanClass, final PropertyUtilsBean propUtils){

        this.beanClassRef = new SoftReference<>(beanClass);
        this.beanClassName = beanClass.getName();
        propertyUtilsBean = propUtils;
        introspect();

    }

    // ----------------------------------------------------- Instance Variables

    /**
     * Name of the JavaBean class represented by this WrapDynaClass.
     */
    private String                                                             beanClassName     = null;

    /**
     * Reference to the JavaBean class represented by this WrapDynaClass.
     */
    private Reference<Class<?>>                                                beanClassRef      = null;

    /** Stores the associated {@code PropertyUtilsBean} instance. */
    private final PropertyUtilsBean                                            propertyUtilsBean;

    /**
     * The set of PropertyDescriptors for this bean class.
     */
    protected PropertyDescriptor[]                                             descriptors       = null;

    /**
     * The set of PropertyDescriptors for this bean class, keyed by the
     * property name. Individual descriptor instances will be the same
     * instances as those in the <code>descriptors</code> list.
     */
    protected HashMap<String, PropertyDescriptor>                              descriptorsMap    = new HashMap<>();

    /**
     * The set of dynamic properties that are part of this DynaClass.
     */
    protected DynaProperty[]                                                   properties        = null;

    /**
     * The set of dynamic properties that are part of this DynaClass,
     * keyed by the property name. Individual descriptor instances will
     * be the same instances as those in the <code>properties</code> list.
     */
    protected HashMap<String, DynaProperty>                                    propertiesMap     = new HashMap<>();

    // ------------------------------------------------------- Static Variables

    private static final ContextClassLoaderLocal<Map<CacheKey, WrapDynaClass>> CLASSLOADER_CACHE = new ContextClassLoaderLocal<Map<CacheKey, WrapDynaClass>>(){

                                                                                                     @Override
                                                                                                     protected Map<CacheKey, WrapDynaClass> initialValue(){
                                                                                                         return new WeakHashMap<>();
                                                                                                     }
                                                                                                 };

    /**
     * Get the wrap dyna classes cache. Note: This method only exists to
     * satisfy the deprecated {@code dynaClasses} hash map.
     */
    @SuppressWarnings("unchecked")
    private static Map<Object, Object> getDynaClassesMap(){
        @SuppressWarnings("rawtypes")
        final Map cache = CLASSLOADER_CACHE.get();
        return cache;
    }

    /**
     * Returns the cache for the already created class instances. For each
     * combination of bean class and {@code PropertyUtilsBean} instance an
     * entry is created in the cache.
     * 
     * @return the cache for already created {@code WrapDynaClass} instances
     */
    private static Map<CacheKey, WrapDynaClass> getClassesCache(){
        return CLASSLOADER_CACHE.get();
    }

    // ------------------------------------------------------ DynaClass Methods

    /**
     * Return the class of the underlying wrapped bean.
     *
     * @return the class of the underlying wrapped bean
     * @since 1.8.0
     */
    protected Class<?> getBeanClass(){
        return beanClassRef.get();
    }

    /**
     * Return the name of this DynaClass (analogous to the
     * <code>getName()</code> method of <code>java.lang.Class</code), which
     * allows the same <code>DynaClass</code> implementation class to support
     * different dynamic classes, with different sets of properties.
     *
     * @return the name of the DynaClass
     */
    @Override
    public String getName(){
        return beanClassName;
    }

    /**
     * Return a property descriptor for the specified property, if it exists;
     * otherwise, return <code>null</code>.
     *
     * @param name
     *            Name of the dynamic property for which a descriptor
     *            is requested
     * @return The descriptor for the specified property
     *
     * @throws IllegalArgumentException
     *             if no property name is specified
     */
    @Override
    public DynaProperty getDynaProperty(final String name){
        if (name == null){
            throw new IllegalArgumentException("No property name specified");
        }
        return (propertiesMap.get(name));

    }

    /**
     * <p>
     * Return an array of <code>ProperyDescriptors</code> for the properties
     * currently defined in this DynaClass. If no properties are defined, a
     * zero-length array will be returned.
     * </p>
     *
     * <p>
     * <strong>FIXME</strong> - Should we really be implementing
     * <code>getBeanInfo()</code> instead, which returns property descriptors
     * and a bunch of other stuff?
     * </p>
     *
     * @return the set of properties for this DynaClass
     */
    @Override
    public DynaProperty[] getDynaProperties(){
        return (properties);
    }

    /**
     * <p>
     * Instantiates a new standard JavaBean instance associated with
     * this DynaClass and return it wrapped in a new WrapDynaBean
     * instance. <strong>NOTE</strong> the JavaBean should have a
     * no argument constructor.
     * </p>
     *
     * <strong>NOTE</strong> - Most common use cases should not need to use
     * this method. It is usually better to create new
     * <code>WrapDynaBean</code> instances by calling its constructor.
     * For example:
     * </p>
     * <code><pre>
     *   Object javaBean = ...;
     *   DynaBean wrapper = new WrapDynaBean(javaBean);
     * </pre></code>
     * <p>
     * (This method is needed for some kinds of <code>DynaBean</code> framework.)
     * </p>
     *
     * @return A new <code>DynaBean</code> instance
     * @throws IllegalAccessException
     *             if the Class or the appropriate
     *             constructor is not accessible
     * @throws InstantiationException
     *             if this Class represents an abstract
     *             class, an array class, a primitive type, or void; or if instantiation
     *             fails for some other reason
     */
    @Override
    public DynaBean newInstance() throws IllegalAccessException,InstantiationException{
        return new WrapDynaBean(getBeanClass().newInstance());
    }

    // --------------------------------------------------------- Public Methods

    /**
     * Return the PropertyDescriptor for the specified property name, if any;
     * otherwise return <code>null</code>.
     *
     * @param name
     *            Name of the property to be retrieved
     * @return The descriptor for the specified property
     */
    public PropertyDescriptor getPropertyDescriptor(final String name){
        return (descriptorsMap.get(name));
    }

    // --------------------------------------------------------- Static Methods

    /**
     * Clear our cache of WrapDynaClass instances.
     */
    public static void clear(){
        getClassesCache().clear();
    }

    /**
     * Create (if necessary) and return a new <code>WrapDynaClass</code>
     * instance for the specified bean class.
     *
     * @param beanClass
     *            Bean class for which a WrapDynaClass is requested
     * @return A new <i>Wrap</i> {@link DynaClass}
     */
    public static WrapDynaClass createDynaClass(final Class<?> beanClass){

        return createDynaClass(beanClass, null);

    }

    /**
     * Create (if necessary) and return a new {@code WrapDynaClass} instance
     * for the specified bean class using the given {@code PropertyUtilsBean}
     * instance for introspection. Using this method a specially configured
     * {@code PropertyUtilsBean} instance can be hooked into the introspection
     * mechanism of the managed bean. The argument is optional; if no
     * {@code PropertyUtilsBean} object is provided, the default instance is used.
     * 
     * @param beanClass
     *            Bean class for which a WrapDynaClass is requested
     * @param pu
     *            the optional {@code PropertyUtilsBean} to be used for introspection
     * @return A new <i>Wrap</i> {@link DynaClass}
     * @since 1.9
     */
    public static WrapDynaClass createDynaClass(final Class<?> beanClass,final PropertyUtilsBean pu){

        final PropertyUtilsBean propUtils = (pu != null) ? pu : PropertyUtilsBean.getInstance();
        final CacheKey key = new CacheKey(beanClass, propUtils);
        WrapDynaClass dynaClass = getClassesCache().get(key);
        if (dynaClass == null){
            dynaClass = new WrapDynaClass(beanClass, propUtils);
            getClassesCache().put(key, dynaClass);
        }
        return (dynaClass);
    }

    // ------------------------------------------------------ Protected Methods

    /**
     * Returns the {@code PropertyUtilsBean} instance associated with this class. This
     * bean is used for introspection.
     *
     * @return the associated {@code PropertyUtilsBean} instance
     * @since 1.9
     */
    protected PropertyUtilsBean getPropertyUtilsBean(){
        return propertyUtilsBean;
    }

    /**
     * Introspect our bean class to identify the supported properties.
     */
    protected void introspect(){
        // Look up the property descriptors for this bean class
        final Class<?> beanClass = getBeanClass();
        PropertyDescriptor[] regulars = getPropertyUtilsBean().getPropertyDescriptors(beanClass);
        if (regulars == null){
            regulars = new PropertyDescriptor[0];
        }
        @SuppressWarnings("deprecation")
        Map<?, ?> mappeds = PropertyUtils.getMappedPropertyDescriptors(beanClass);
        if (mappeds == null){
            mappeds = new HashMap<>();
        }

        // Construct corresponding DynaProperty information
        properties = new DynaProperty[regulars.length + mappeds.size()];
        for (int i = 0; i < regulars.length; i++){
            descriptorsMap.put(regulars[i].getName(), regulars[i]);
            properties[i] = new DynaProperty(regulars[i].getName(), regulars[i].getPropertyType());
            propertiesMap.put(properties[i].getName(), properties[i]);
        }
        int j = regulars.length;
        final Iterator<?> names = mappeds.keySet().iterator();
        while (names.hasNext()){
            final String name = (String) names.next();
            final PropertyDescriptor descriptor = (PropertyDescriptor) mappeds.get(name);
            properties[j] = new DynaProperty(descriptor.getName(), Map.class);
            propertiesMap.put(properties[j].getName(), properties[j]);
            j++;
        }
    }

    /**
     * A class representing the combined key for the cache of {@code WrapDynaClass}
     * instances. A single key consists of a bean class and an instance of
     * {@code PropertyUtilsBean}. Instances are immutable.
     */
    private static class CacheKey{

        /** The bean class. */
        private final Class<?>          beanClass;

        /** The instance of PropertyUtilsBean. */
        private final PropertyUtilsBean propUtils;

        /**
         * Creates a new instance of {@code CacheKey}.
         *
         * @param beanCls
         *            the bean class
         * @param pu
         *            the instance of {@code PropertyUtilsBean}
         */
        public CacheKey(final Class<?> beanCls, final PropertyUtilsBean pu){
            beanClass = beanCls;
            propUtils = pu;
        }

        @Override
        public int hashCode(){
            final int factor = 31;
            int result = 17;
            result = factor * beanClass.hashCode() + result;
            result = factor * propUtils.hashCode() + result;
            return result;
        }

        @Override
        public boolean equals(final Object obj){
            if (this == obj){
                return true;
            }
            if (!(obj instanceof CacheKey)){
                return false;
            }

            final CacheKey c = (CacheKey) obj;
            return beanClass.equals(c.beanClass) && propUtils.equals(c.propUtils);
        }
    }
}
